Hello everyone,

I have a 2008 Trailblazer, during winter I had 3 times where i need to get a jump, it would not start.

I took it to Autozone Then said Alternator was bad....

2nd opinion was O'Reillys Then said Alternator was fine Its the battery !!

Well now, I wanted a

3rd opinion .... Advance Auto Parts, They could not give me an answer , After testing they we lost... I mean Lost..


So I bought a new battery...seems to be ok..When I looked at the battery gauge it said 15 volts.. While running


So though problem was fixed.

But last week I noticed the gauge went from 15 volts to 12 volts while running. So I bought a new, not re manufactured Alternator and starting the truck is at 15.5volts .

Sometime I drive for 30 minutes other times 10 No consistency.. But the Battery indicator goes from 15 volts to to 12.5 V

Any Ideas. When the gauge showed 13 volts, I verified it with my Volt Meter It was correct. So I am ruling out the Gauge as the problem.

Thank you

 

Check your cables to and from the battery and alternator. Check them at both ends for looseness and corrosion.

 

Ok did that found nothing wrong.
Its wierd I can make a 30 min trip with no stops and the gauge stays on 15-14 volts. ON the way home I get 15 minutes in to the trip and I see the voltage going down, to 12 volts.. Could a work Serpentine belt cause this?

Can the computer be causing this?

Here what I fine that may be the problem Regulated Voltage Control Module, any thoughts.

 

You are chasing a non existent problem unless you are ending up with dead batteries. The computer adjusts the charging voltage according to load , battery temp and some other parmameters and it will range anywhere from around 15 volts to down around 12 when there is low load on the battery and charging system . This is normal behavior and even says so in the owners manual .